1. Field of the Invention
The present invention is related to automated and semi-automated immuno-assays and methods for performing an immuno-assay. Specifically, this invention is an automated apparatus and method for performing blot assays such as the Western Blot Assay.
2. Description of the Background Art
Currently available automated and semi-automated assays are based primarily on an enzyme-linked immunosorbent assay (ELISA). An ELISA is used to detect proteins including antigens and antibodies. Once a positive result is obtained with an ELISA, a Western Blot Assay is often used to more accurately analyze or confirm the analysis. The Western Blot Assay provides a sensitive analysis, but is not currently performed by an automated means. For this reason, the performance of a Western Blot Assay for similar assay requires many manual procedures and is, therefore, expensive and subject to human error. The operator of such an analysis is at some risk of contact with the pathogens that are being analyzed.
U.S. Pat. No. 4,520,113 to Gallo et al. discloses a method for detecting antibodies characteristic of AIDS using antigen from the virus HTLV-III. Antigens associated with this virus are specifically recognized by antibodies from AIDS patients. The detection of the antigen is performed by strip radioimmunoassay based on the Western Blot technique, ELISA (most preferred), or indirect immunofluorescence assay. This method is not automated.
PCT Application No. 8,504,903 by Gallo et al. discloses use of a Western blot and a competition immunoassay to detect HIV antibodies. Protein bands are formed by electrophoresis of HIV on a polyacrylamide gel in the presence of sodium dodecyl sulphate. The bands are transferred to a nitrocellulose sheet which is then separated into strips. The strips are then used as antigenic reagents in a competition immunoassay. The test can be used in screening for AIDS. The test is not automated, and does not provide safety or convenience.
Gordon, U.S. Pat. No. 4,452,901 describes the electrophoretic transfer of proteins from gels to nitrocellulose. The immobilized proteins may then be used for the immunodetection of antigens or antibodies.
U.S. Pat. No. 4,720,463 to Farber et al. discloses an automated microbiological testing apparatus. An incubation chamber holds multiple microbiological test trays. Tray carriers move the trays to an inspection station. The image on the tray is processed to determine test results. This apparatus and method allows neither rocking of the samples nor the automatic sequential addition and removal of reagents and washing solutions.
U.S. Pat. No. 3,535,208 to Sasaki et al. discloses an apparatus that provides a rocking motion for samples. The primary purpose of the rocking motion in this invention is to provide heat transfer. Each sample in a series of samples has a different proportion of its wall or container surface area in contact with a heating or cooling chamber. Each sample, therefore, reaches a different temperature during the rocking motion. This apparatus allows temperature dependence of a reaction to be determined in a single apparatus with a single experiment. The apparatus does not allow the sequential addition and removal of reagents and washing solutions.
The industry is lacking a fully automated means for performing the Western Blot Assay and similar assays that is economical, safe, accurate, and convenient to use.